Recent studies show that the analysis of the brain's electrical fields with the electroencephalogram (EEG) could produce an informative, cost-effective method of neuroimaging if the density of scalp electrodes were increased substantially over conventional practice. We propose to commercialize an apparatus that attaches 128 EEG electrodes in an even spatial array across the surface of the human head. This apparatus comprises two specific inventions by Tucker (patents pending). The first is a method for positioning sensors for individual head geometries by a network tensional structure of elastic lines forming the geodesic partitioning of a spherical surface. The second invention is a sensor pedestal, a simple device that attaches at the vertices of the geodesic triangles, such that the compression directed radially by the tensional network toward the sphere center is used to hold a simple Ag/AgCl sponge electrode against the scalp. The Geodesic Electrode Net can be applied within half an hour and worn comfortably for several hours. With appropriately-designed, inexpensive amplifiers, it yields excellent EEGs. Our visual event-related potential (ERP) data with 64-channel arrays confirms the need for dense electrode arrays to adequately characterize the information on brain activity available from the scalp EEG.